Synthesis of o-quinodimethanes and benzocyclobutenes from dimethyl squarate
Published Web Locationhttps://doi.org/10.1016/s0040-4039(00)73703-8
Selected 3-alkylidene(and benzylidene)-4-allenylcyclobutenes were shown to undergo an unusual thermal ring expansion to o-quinodimethanes and thus to benzocyclobutenes upon electrocyclic ring closure. The mechanism of this rearrangement is envisaged to involve ring opening of the starting cyclobutenes to the corresponding octa-1,2,4,6,7-pentaenes which lead to the quinodimethanes upon ring closure. © 1993.